A server can provide a publish-subscribe mechanism that enables clients of the server to obtain content from the server. For example, a messaging server can provide a publish-subscribe mechanism that enables clients of the messaging server to subscribe to and receive messages published by the messaging server.
A client of a publish-subscribe mechanism can miss out on messages published before a subscription is established. In addition, a client of a publish-subscribe mechanism can miss out on messages when network transmission errors occur, or when the client fails to keep up with the rate of message publication.